Validate change-notes in PRs

This commit also introduces the 'empty' home directory for future change-notes.

Author: mario-campos

.github/workflows/pr-checks.yml

@@ -255,3 +255,32 @@ jobs:
           else
             echo "Skipping repo size comment because the delta is below the threshold and no sticky comment exists."
           fi
+
+  validate-change-notes:
+    name: Validate change notes
+    if: github.triggering_actor != 'dependabot[bot]'
+    permissions:
+      contents: read
+    runs-on: ubuntu-slim
+
+    concurrency:
+      cancel-in-progress: true
+      group: pr-checks-validate-change-notes-${{ github.ref }}-${{ github.event_name }}
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+
+      - name: Set up Node.js
+        uses: actions/setup-node@820762786026740c76f36085b0efc47a31fe5020 # v7.0.0
+        with:
+          node-version: 24
+          cache: 'npm'
+
+      - name: Install dependencies
+        run: npm ci
+
+      - name: Run `changetool validate`
+        # "unreleased-change-notes" resolves to a path relative to scripts/changetool.
+        # So, we need to pass the absolute path to the directory by prefixing $GITHUB_WORKSPACE.
+        run: npm --workspace changetool start validate "$GITHUB_WORKSPACE/unreleased-change-notes"